The present invention relates generally to the field of communication, and, more particularly, to communication using time division multiple access (TDMA) technology.
Wireless communication systems are commonly used to provide voice and data communication services to subscribers. A typical terrestrial cellular radiotelephone communication system 20 is illustrated in FIG. 1. The cellular radiotelephone system 20 may include one or more radiotelephones or mobile terminals 22a,b,c, that communicate via a plurality of cells 24a,b,c served by base stations 26a,b,c and a mobile switching center (MSC) 28. Although only three cells 24a,b,c are shown, a typical cellular network may include hundreds of cells, multiple MSCs 28, and may serve thousands of radiotelephones 22a,b,c. 
The cells 24a,b,c generally serve as nodes in the communication system 20 from which links are established between the radiotelephones 22a,b,c and the MSC 28 by way of the base stations 26a,b,c serving the cells 24a,b,c. Each cell 24a,b,c will typically have allocated to it one or more dedicated control channels and one or more traffic channels. A control channel is a dedicated channel used for transmitting cell identification and paging information. A traffic channel carries the voice and data information. Through the cellular network 20, a duplex radio communication link may be established between two radiotelephones 22 or between a radiotelephone 22 and a wireline telephone user 32 through the public switched telephone network (PSTN) 34. A function of the base stations 26a,b,c is to handle radio communication between the cells 24a,b,c and the radiotelephones 22a,b,c. In this capacity, the base stations 26a,b,c may function as a relay station for data and voice signals.
The radiotelephones 22a,b,c may be designed to communicate using, for example, frequency division multiple access (FDMA) technology (e.g., the advanced mobile phone service (AMPS) standard); time division multiple access (TDMA) technology (e.g., the Telecommunication Industry Association (TIA)/Electronic Industries Association (EIA) 136 or digital AMPS (DAMPS) standard or the global system for mobile communication (GSM) standard); or code division multiple access (CDMA) technology (e.g., the TIA interim standard (IS) 95). The FDMA and TDMA technologies will be discussed in more detail hereafter.
Traditional analog cellular systems generally use FDMA to create communication channels. Radiotelephone communication signals are generally modulated waveforms that are communicated over predetermined frequency bands in a spectrum of carrier frequencies. In a typical FDMA system, each of these discrete frequency bands may serve as a channel over which cellular radiotelephones communicate with a base station or satellite serving a cell.
As the number of subscribers in a cellular radiotelephone system increases, the available frequency spectrum may need to be managed with greater efficiency to provide more channels while maintaining communication quality. This challenge may be further complicated because subscribers may not be uniformly distributed among cells in the system. More channels may be needed for particular cells to handle potentially higher local subscriber densities at any given time. For example, a cell in an urban area might contain hundreds or thousands of subscribers at certain times, which may exhaust the number of channels available in the cell.
To provide service to increasing numbers of subscribers, conventional cellular systems may implement frequency reuse to increase channel capacity in each cell and increase spectral efficiency. More specifically, frequency bands may be allocated to each cell such that cells using the same frequencies are geographically separated to allow radiotelephones in different cells to use the same frequency simultaneously without interfering with each other. Accordingly, many thousands of subscribers may be served by a system having only several hundred allocated frequency bands.
Another technology that may further increase channel capacity and spectral efficiency is TDMA. A TDMA system may be implemented by subdividing the frequency bands used in conventional FDMA systems into sequential time slots. Communication over a frequency band typically occurs via a repetitive TDMA frame structure wherein each frame includes a plurality of time slots. Each radiotelephone communicates with the base station using bursts of digital data transmitted during the radiotelephone""s assigned time slots.
A channel in a TDMA system may include at least one time slot on at least one frequency band, and typically includes at least one time slot in each of a plurality of frames. As discussed in the foregoing, channels may be used to communicate voice, data, or other information between users, e.g., between a radiotelephone and a wireline telephone. Predetermined time slots of predetermined frequency bands may be allocated for dedicated control channels. These dedicated control channels may include forward control channels, which are used to broadcast control information in a cell of the radiotelephone system to radiotelephones which may seek to access the system. The control information broadcast on a forward control channel may include such information as the cell""s identification, associated network identification, system timing information, and other information needed to access the radiotelephone system from a radiotelephone.
Traditional radiotelephones or mobile terminals may include a serial data port in which a device, such as a computer or personal digital assistant (PDA), may be connected to establish a wireless data connection. Moreover, a cellular network may include such communication devices known as xe2x80x9cwireless communicators,xe2x80x9d which are being used in ever increasing numbers for voice calls, data calls, facsimile transfer, Internet access, paging, and other personal organization features such as calendar management or even travel directions via the Global Positioning System (GPS). As used herein, the term xe2x80x9cwireless communicatorxe2x80x9d may include a cellular radiotelephone with a multi-line display, a Personal Communications System (PCS) terminal that may combine a cellular radiotelephone with data processing, facsimile and data communications capabilities, a PDA that can include a radiotelephone, pager, Internet/intranet access, Web browser, organizer, calendar and/or a GPS receiver, and conventional laptop and/or palmtop receivers that include radiotelephone transceivers. Wireless communicators also may be referred to as xe2x80x9cpervasive computingxe2x80x9d devices.
In view of the capabilities of wireless communicators, radiotelephones, PDA devices, and the like, there exists a need for improved communication devices that can provide voice and data services.
Communication devices, methods, and computer program products may acquire a first time division multiple access (TDMA) time slot on a TDMA carrier frequency to establish a first call and acquire a second TDMA time slot on the TDMA carrier frequency to establish a second call. The first and second time slots may be associated with a single TDMA frame of the TDMA carrier frequency, which may allow, for example, a voice call and a data call to be established concurrently. Accordingly, the need for multiple phones to maintain both a voice connection and an Internet connection concurrently on a TDMA network may be obviated. As a result, a user need not carry two separate phones having separate phone numbers and electronic serial numbers and the additional weight and bulk of multiple batteries and battery chargers.
In accordance with an aspect of the invention, a communication device may include a controller that configures a transmit switch to selectively connect a voice source and a data source to a transmit interface based on the TDMA time slots allocated to respective voice and data calls. Similarly, the controller configures a receive switch to selectively connect a voice destination and a data destination to a receive interface based on the TDMA times slots allocated to the respective voice and data calls.
In accordance with another aspect of the invention, the first and second TDMA time slots used to establish the first and second calls may each comprise a full rate TDMA time slot. In accordance with yet another aspect of the invention, a communication device may acquire all time slots on the TDMA carrier frequency when establishing concurrent calls. In accordance with still another aspect of the invention, a base station may send a signal to a communication device that indicates whether one or more of the time slots are available on the TDMA carrier frequency.
The present invention, therefore, may allow a communication device to make concurrent voice and data calls on the same TDMA carrier frequency by allocating one full rate time slot on the carrier frequency to the voice call and one full rate time slot on the carrier frequency to the data call. Inasmuch as the two full rate time slots are on the same TDMA carrier frequency, additional frequency synthesizers or tuning of existing frequency synthesizers may not be required.